1. Field of the Invention
The present invention relates generally to computer systems, and more particularly but not exclusively to differential compression and incremental file update.
2. Description of the Background Art
Computer files may need to be updated for a variety of reasons. As a particular example, computer security programs need to be periodically updated to incorporate new virus signatures, new document fingerprints (for data loss prevention), newly developed detection algorithms, and so on. An updated version of a file of a program may be generated in one computer and distributed to multiple computers that subscribe to receive updates. Subscribing computers receive the updated version of the file over a computer network, making it important to minimize the size of updates to reduce network bandwidth consumption.
One way of minimizing the size of updates is to perform a difference procedure on the updated version and old version of a file to generate a difference file, and send the difference file instead of the updated version of the file to subscribing computers. In a subscribing computer, the difference file is merged with the old version of the file to reconstruct the updated version of the file. Differential compression allows for reduced network bandwidth consumption and storage use because the resulting difference file is relatively small.